# include "scene.h"

# include <stdio.h>
# include <stdlib.h>
# include <math.h>

/* This function accepts the temperature in Kelvin and returns kinematic viscosity of the water. */
extern double kvisc(double T)
  {
   FILE *ptr;

#  ifdef RETURN_CONST_KVISC
   T = T_INIT;
#  endif

   T -= ABS_ZERO;

   if( (T < 0) || (T > 100) )
       {
        if((ptr = fopen("kvisc_log.txt", "w")) == (FILE*)0) ptr = stderr;

        fprintf(ptr, "ERROR:: In function 'kvisc()': \"T = %E Kelvin\"; However, it should be \"%E K <= T <= %E K\"\n",\
                      T+ABS_ZERO, 0+ABS_ZERO, 100+ABS_ZERO);

        if(ptr != stderr) fclose(ptr);
        exit(-1);
       }

   return 2.67E-7 + 1.481E-6*exp(-0.03381*T);
  }
